March 2011 - Boost-users - lists.preview.boost.org

[units] Creating specific unit quantities
by Ryan 17 Mar '11

17 Mar '11

In the Boost Unit documentation there are examples on creating quantities using a dimension. There doesn't seem to be any documentation on using a specific type of dimension as a quantity. Is it possible to create a quantity with a specific type of dimension value? using namespace boost::units; using namespace boost::units::si; quantity<length> L = 2.0*meters; //Is it possible to have meters instead of length as a quantity? quantity<???> L = 2.0 * meters; Ryan

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Library Developers Battling Cyclic Header Dependency
by Ryan 17 Mar '11

17 Mar '11

In the boost library system certain libraries need to be compiled and linked into a project. For example, libraries would need to be compiled to remove cyclic header dependencies. In the boost library system I coundn't find any .cpp files that would indecate a compilable library. So how do library developers create compilable files in the boost libraries? The following two files would need to be broken up and compiled to remove the dependencies, correct? Ryan //File A.hpp class B; class A { double x; public: B convertToB(void) { return B(x); } }; //File B.hpp class A; class B { double y; public: A convertToA(void) { return A(y); } };

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[Serialization] Segfault while serializing derived pointers using multi DLLs
by François Mauger 17 Mar '11

17 Mar '11

Hi all (and particularly Boost/(De-)Serializer), I use Boost 1.44, gcc 4.4.1, Linux. The problem: I have two home made libraries compiled as DLL under linux: - 'datatools' provides the 'libdatatools.so' DLL - 'brio' provides the 'libbrio.so' DLL I use Boost serialization features for derived pointers. Below are the details: STEP 1: 'datatools' is the base library. It defines: - its own namespace: 'datatools' - a virtual class (interface) named 'i_serializable' from which all other serializable classes should inherit in order to benefit of the (de)serialization mechanism through pointer to this base class. [see http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/serialization.h…] - some concrete classes (A, B, C) that inherit from the 'i_serializable' interface and register themselves using the export key features described in http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/special.html#ex… Typical inheritance diagram looks like: <pre> datatools::i_serializable | +--------------+--------------+ | | | datatools::A datatools::B datatools::C | datatools::A' </pre> Here is the typical model of the 'A.hpp' header file for the A class: <pre> ... #include <datatools/serialization/archives_list.hpp> // include Boost/Serialization text/XML/binary archives #include <datatools/serialization/i_serializable.hpp> // include the abstract mother interface class ... namespace datatools { class A: public i_serializable { blah-blah.. // no inline code (from http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/special.html#dl…) template<class Archive> void serialize (Archive & ar, const unsigned int version); }; } // register the class with a specific GUID: BOOST_CLASS_EXPORT_KEY2 (datatools::A, "datatools::A"); </pre> Here is the model of the 'A.cpp' implementation file: <pre> namespace datatools { ... template<class Archive> void A::serialize (Archive & ar, const unsigned int version) { ar & boost::serialization::make_nvp( "datatools__serialization__i_serializable", boost::serialization::base_object<datatools::serialization::i_serializable >(*this) ); ar & more data (with NVP stuff)...; } } // end of namespace datatools BOOST_CLASS_EXPORT_IMPLEMENT(datatools::A) // explicit instantiation for all kind of known archives: #include <datatools/serialization/archives_list.hpp> // include the known text/XML/binary archives template void datatools::A::serialize(boost::archive::text_oarchive & ar, const unsigned int version); template void datatools::A::serialize(boost::archive::text_iarchive & ar, const unsigned int version); template void datatools::A::serialize(boost::archive::xml_oarchive & ar, const unsigned int version); ... more... </pre> Finaly, I can compile all this stuff using gcc and build the 'libdatatools.so' library which I prepend to my LD_LIBRARY_PATH. Everything looks fine. A test program 'prg1.cpp' that links against only 'libdatatools.so' and 'libboost_serialization.so' works prefectly, serialiazing and deserialiazing any collection of pointers to A,B, or C classes without problem. A must ! Thanks to Robert for that magic ! At this point, everything looks (is?) fine. Note that I have followed (in principle) all the guidelines provided by Robert. STEP 2: Now let's consider the actual problem ! As said before, my 'datatools' library is the base of some modular project with some other libraries that depend on 'datatools' (and Boost/Serialization). The 'brio' library is such a beast: <pre> Boost/Serialization | datatools | brio </pre> It has its own namespace: 'brio' It provides a few other dedicated classes, inherited from the 'datatools::i_serializable' abstract class and which are serializable via Boost. Let's consider the serializable 'brio::D' class, designed on the model of 'datatools::A' and using the same implementation recommendations. I have followed the guidelines use for the 'datatools::A' class to write both 'D.hpp' and 'D.cpp' files. Now the inheritance scheme is: <pre> datatools::i_serializable : | : +--------------+--------------+------------+-----+- - - - | | | : | datatools::A datatools::B datatools::C : brio::D | : datatools::A' : libdatatools.so scope : libbrio.so scope : </pre> I can compile the 'libbrio.so' DLL without any problem. Now I want to run a sample program 'prg2.cpp' that performs some (de)serialization operations on a collection of pointers to 'datatools::A', 'datatools::B', 'datatools::C' AND 'brio::D' instances. This program is linked against the following libraries (among others): - libbrio.so - libdatatools.so - libboost_serialization.so Well, it compiles perfectly. Note this program links against third-party libraries too, among them some are explicitely using 'dlopen' and 'dlclose' to satisfy internal and critical features that are out of my scope. I have no idea if this can have side-effect. However, when I run it, I observed the following behaviour: - all (de)serialization operations are done properly and I get files with embeded (text/XML...) portable archives than can be reloaded without problem. - at the END of the program, while some cleaning code is invoked (some kind of deep buried code out of my skills and understanding), I get a Segmentation fault. Here is a dump of the GDB backtrace: <pre> Program received signal SIGSEGV, Segmentation fault. 0x02647c78 in boost::serialization::typeid_system::extended_type_info_typeid_0::is_less_than(boost::serialization::extended_type_info const&) const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 (gdb) bt #0 0x02647c78 in boost::serialization::typeid_system::extended_type_info_typeid_0::is_less_than(boost::serialization::extended_type_info const&) const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #1 0x0264737b in boost::serialization::extended_type_info::operator<(boost::serialization::extended_type_info const&) const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #2 0x0264dcac in boost::serialization::void_cast_detail::void_caster::operator<(boost::serialization::void_cast_detail::void_caster const&) const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #3 0x0264e56d in boost::serialization::void_cast_detail::void_caster::recursive_unregister() const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #4 0x0264ed8d in boost::serialization::void_cast_detail::void_caster_shortcut::~void_caster_shortcut() () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #5 0x0264e5ee in boost::serialization::void_cast_detail::void_caster::recursive_unregister() const () from /scratch/sw/boost/install-1_44_0-Linux-i686-gcc44/lib/libboost_serialization.so.1.44.0 #6 0x024a6da7 in boost::serialization::void_cast_detail::void_caster_primitive<datatools::test::more_data_t, datatools::test::data_t>::~void_caster_primitive() () from /home/mauger/Private/Work/lpc_nemo_svn/sw/datatools/datatools_trunk/Linux-i686/lib/libdatatools.so #7 0x024a6f04 in boost::serialization::detail::singleton_wrapper<boost::serialization::void_cast_detail::void_caster_primitive<datatools::test::more_data_t, datatools::test::data_t> >::~singleton_wrapper() () from /home/mauger/Private/Work/lpc_nemo_svn/sw/datatools/datatools_trunk/Linux-i686/lib/libdatatools.so #8 0x0298c428 in __cxa_finalize (d=0x2609830) at cxa_finalize.c:56 #9 0x02426f04 in __do_global_dtors_aux () from /home/mauger/Private/Work/lpc_nemo_svn/sw/datatools/datatools_trunk/Linux-i686/lib/libdatatools.so #10 0x02534100 in _fini () from /home/mauger/Private/Work/lpc_nemo_svn/sw/datatools/datatools_trunk/Linux-i686/lib/libdatatools.so #11 0x0011dee6 in _dl_fini () at dl-fini.c:248 #12 0x0298c05f in __run_exit_handlers (status=0, listp=0x2a9e304, run_list_atexit=true) at exit.c:78 #13 0x0298c0cf in *__GI_exit (status=0) at exit.c:100 #14 0x02973b5e in __libc_start_main (main=0x8059495 <main>, argc=1, ubp_av=0xbfffcfd4, init=0x8061c40 <__libc_csu_init>, fini=0x8061c30 <__libc_csu_fini>, rtld_fini=0x11dcc0 <_dl_fini>, stack_end=0xbfffcfcc) at libc-start.c:252 #15 0x080592c1 in _start () at ../sysdeps/i386/elf/start.S:119 </pre> If one ignores the nasty details from this stack (local pathes and names), one observe that the problem seems to be related to some unregistration of some Boost/Serialization material. It occurs while the executable is trying to destruct some singleton_wrapper template class that manages some serializable classes from the 'datatools' library: - class 'datatools::test::more_data_t' (call it A') - and its mother class 'datatools::test::data_t', (call it A) inherited from 'datatools::i_serializable'. I expect such singleton is a static instance attached in some DLL. Am I wrong ? If not, which DLL is concerned 'libdatatools.so', 'libbrio.so' ? My feeling is that I have a problem with some arbitrary order of library unloading and messy unregistration that comes with. Unless there is a specific order to aggregate module within in DLL (A.o B.o A'.o...). Unfortunately, my skills are too limited to make a better idea and find a solution. There is some comments by Robert concerning such possible problems, but I'm not sure it makes sense in my case. So I will really appreciate if someone could advise me and possibly give me some hints. Thanks a lot for attention and help. Apologize for this rather long and technical issue. Regards frc -- François Mauger Groupe "Interactions Fondamentales et Nature du Neutrino" NEMO-3/SuperNEMO Collaboration LPC Caen-CNRS/IN2P3-UCBN-ENSICAEN Département de Physique -- Université de Caen Basse-Normandie Adresse/address: Laboratoire de Physique Corpusculaire de Caen (UMR 6534) ENSICAEN 6, Boulevard du Marechal Juin 14050 CAEN Cedex FRANCE Courriel/e-mail: mauger(a)lpccaen.in2p3.fr Tél./phone: 02 31 45 25 12 / (+33) 2 31 45 25 12 Fax: 02 31 45 25 49 / (+33) 2 31 45 25 49

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[lexical_cast] crash using Intel 12.0 with optimizations enabled
by Thomas Mang 17 Mar '11

17 Mar '11

Hi, I tracked down a crash to a call to boost::lexical_cast (Boost 1.46.1( when using the Intel 12.0 compiler for Windows (embedded into MSVC8) if optimizations are enabled. I would have expected the mini-program below to work smoothly, but instead the second catch-handler is entered (unknown exception). The offending compiler option is /O; in all cases except of /Od [all optimizations disabled] the exception is raised. May I strongly suppose this is either a boost or an Intel compiler issue, or did I misunderstand something ? Below are full command-line compiler options and teh program. Thanks and best, Thomas command line options: /c /O2 /Og /Qipo /I "C:\Libraries\Boost\boost_1_46_1" /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /EHsc /MD /GS- /fp:strict /Za /Fo"ReleaseFinal/" /W3 /nologo /Wp64 /Zi /Qfp-speculation:strict /Quse-intel-optimized-headers /Qintel-extensions- mini-program: #include <iostream> #include <ostream> #include <string> #include "boost/lexical_cast.hpp" int main() { try { std::string X = boost::lexical_cast<std::string>(2 - 1); std::cout << X << std::endl; } catch (boost::bad_lexical_cast const &) { std::cout << "boost::lexical_cast exception occurred."; } catch (...) { std::cout << "An unknown exception occurred."; } }

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Compiling Boost with 4 byte packing...
by Brian Nantz 17 Mar '11

17 Mar '11

I am trying to get boost asio to work with my code (which is using 4 byte struct member alignment and _cdecl calling convention). I get the following error when calling asio::async_write: Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention. What am I missing? I have read everything on ABI that I can find: http://www.boost.org/development/separate_compilation.html I changed boost\config\abi\msvc_prefix.hpp to use #pragma pack(push,4). I also am using the command line option for bjam: cxxflags="/Zp4 /Gd" The Microsoft documentation seems to indicate that the /Zp should override the #pragma if the #pragma is larger or equal: http://msdn.microsoft.com/en-us/library/ms253935.aspx http://msdn.microsoft.com/en-us/library/46t77ak2.aspx Any help would be greatly appreciated, Brian

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[boost-user][asio]How can i limit tcpserver's connection count?
by rhapsodyn 16 Mar '11

16 Mar '11

here‘s the code server： class tcp_server { public: tcp_server(boost::asio::io_service& io_service) : acceptor_(io_service),limit(0) { tcp::endpoint endpoint(tcp::v4(), 10000); acceptor_.open(endpoint.protocol()); acceptor_.bind(endpoint); acceptor_.listen(1); start_accept(); } private: void start_accept() { while(1) { if(limit < 1) break; } tcp::socket* socket = new tcp::socket(acceptor_.io_service()); acceptor_.async_accept(*socket, boost::bind( &tcp_server::handle_accept, this, socket, boost::asio::placeholders::error)); } void handle_accept(tcp::socket* s, const boost::system::error_code& error) { if (!error) { ++limit; start_accept(); } } tcp::acceptor acceptor_; int limit; }; client： int main(int argc, char* argv[]) { int i = 0; try { boost::asio::io_service io_service; tcp::resolver resolver(io_service); tcp::resolver::query query("127.0.0.1", "10000"); tcp::resolver::iterator endpoint_iterator = resolver.resolve(query); tcp::endpoint endpoint = *endpoint_iterator; tcp::socket socket(io_service); socket.connect(endpoint); while(1) {} } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; } I thought i can only launch 1 client, but fact is: i can start two clients and the 3rd one just cerr the what(), what happend there? Is there some better way to get & limit the "living-connection" of the server? -- View this message in context: http://boost.2283326.n4.nabble.com/boost-user-asio-How-can-i-limit-tcpserve… Sent from the Boost - Users mailing list archive at Nabble.com.

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boost::asio::write(), big data-chunks, socket-error 10053
by Sebastian Rudek 15 Mar '11

15 Mar '11

Hello I am having trouble with Sockets under Windows and Linux. When attempting to send much data through boost::asio::write(), the socket error 10053 - connection aborted - occurs. I am sending from a Windows machine over the local network to a server (not using boost), running on linux. This server uses a select to determine whether there is something to read or not. Sending not lots of data, for example 500 bytes, does not fail. But sending some hundred of kilobytes or even megabytes, fails. Does a timeout occur? why? and how can i make my client to transfer all of its data? did you experience something similar? Thanks in advance, regards Sebastian -- Sebastian Rudek, Softwareentwickler Lyncker& Theis GmbH Wilhelmstr. 16 65185 Wiesbaden Germany Fon +49 611/9006951 Fax +49 611/9406125 Handelsregister: HRB 23156 Amtsgericht Wiesbaden Steuernummer: 4323897052 USt-IdNr.: DE255806399 Geschäftsführer: Filip Lyncker, Armin Theis, Patrick Schmidt

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boost::bind can't bind bind_t type right?
by ???? 15 Mar '11

15 Mar '11

#include <iostream> #include <boost/bind.hpp> #include <boost/function.hpp> class test1 { public: template<typename S> double handle(S s) { s(1); std::cout<<"test1\n"; return 1; } template<typename F> void handle1(F f){ boost::bind(&test1::handle<F>,this,f)(); } }; class test2 { public: double handle(int i) { std::cout<<"test2\n"; return i; } }; int _tmain(int argc, _TCHAR* argv[]) { test2 t2; test1 t1; t1.handle1(boost::bind(&test2::handle,t2,_1)); return 0; } in test1::handle1 complie fail on vs2010 and gcc 4.4.1 vs 2010 error:error C2664: "R boost::_mfi::mf1<R,T,A1>::operator ()<test1>(const U &,A1) const": can't convert "double"to "boost::_bi::bind_t<R,F,L>" . but boost::bind(&test1::handle<F>,this,f)(); f is not double,f is bind_t and double only return_type. by the way,boost::bind(&test1::handle<F>,this,boost::ref(f))(); can work.

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[Regex] Search Substring with paranthesis
by Subhash Nagre 15 Mar '11

15 Mar '11

Hello, I have a string "(123) Hello" and I want to seach String (123) using boost::regex, Also I needed to do a full word search, so I added \b in the end. Here is my code std::string searchWord = "(123)"; searchWord += "\\" + "b"; // Step 1 boost::regex expression; expression.assign(searchWord); std::string completeStr = "(123) Hello (123)"; std::string::const_iterator start = completeStr.begin(); std::string::const_iterator end = completeStr.end(); boost::smatch what; while (boost::regex_search(start, end, what, expression)) { int32 foundPos = what.position(); int32 foundLen = what.length(); std::string foundString(start + foundPos, start + foundPos + foundLen); //This foundStr is 123, beacuse it finds a metacharacter in the seach expression // Perform some task with foundString start += foundPos + foundLen; } How Can I get (123) back and foundPos and foundLen as 0 and 5 respetively. I tried creating my search expression as /(123/), but it didn't worked. Also if I don't add \b in the search expression in Step 1, even in that case the foundStr is 123 but in that case, the match will be true even for (1234), which I don't want. I want to find full words only. Is there is any flag in boost::regex which can help me out or how can I perform my task. Thanks in advance Subhash

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[1.46.1] Boost 1.46.1 Release available
by Beman Dawes 15 Mar '11

15 Mar '11

Release 1.46.1 of the Boost C++ Libraries is now available. These open-source libraries work well with the C++ Standard Library, and are usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use. This is a bug fix release that is otherwise the same as 1.46.0. For details, including download links, see http://www.boost.org/users/news/version_1_46_1 The release can also be downloaded directly from SourceForge. See http://sourceforge.net/projects/boost/files/ To install this release on your system, see http://www.boost.org/doc/libs/release/more/getting_started/index.html Thanks, --The Boost release team Beman Dawes Daniel James Eric Niebler Rene Rivera Vladimir Prus

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[StateChart] pass objectpointer to FSM?
by Bernt-Johan Bergshaven 15 Mar '11

15 Mar '11

Hello, first; thank you for an excellent library collection. I recently discovered it, and I'm impressed! My question: How can I pass a pointer to an object into the state machine? I want to use my state machine to control a real-life elevator. All the functions for controlling this elevator is inside class Elevator; I.e: myElevator->startEngine(UP); I've tried different approaches as you might see in my attached code, but I keep getting this error: statemachine: ../boost/boost/cast.hpp:97: Target boost::polymorphic_downcast(Source*) [with Target = ElevatorSM*, Source = boost::statechart::state_machine<ElevatorSM, ElevatorActive>]: Assertion `dynamic_cast<Target>(x) == x' failed. Aborted h-file: http://codepad.org/i3rAjT1p cpp-file: http://codepad.org/TpaWluCz Appreciate your help, Bernt-Johan Bergshaven, Norway

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how to create a tuple from an mpl sequence?
by Peter Foelsche 15 Mar '11

15 Mar '11

I've got some mpl sequence from which I want to create a tuple. Anybody any clue? I also looked into fusion (why is there so much overlap to mpl?) but did not find anything. Tried fusion::result_of::push_back without much success. Tried fusion::vector with fusion::result_of::push_back . Does this functionality exist? Peter

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[uBLAS] Identity Matrix Constructor vs Resize
by Ryan 14 Mar '11

14 Mar '11

I have an identity matrix that when initialized with the constructor I don't get an error. If I do a default construction and then resize the matrix I get a runtime error. I'm not sure the difference. Could someone enlighten me? Ryan using namespace boost::numeric::ublas; template<typename matrixT> matrix_range<matrixT> topleft (matrixT & M) { return subrange(M, 0, 3, 0, 3); } int main(int, char const* []) { vector<double> initial(3); initial[0] = 10; initial[0] = 100; initial[0] = 2; //I realize that "matrix<double> P(zero_matrix<double>(9,9));" would do the same thing as below. //This is extracted from a class and the constructor needs to to this. matrix<double> P; //This is a class variable P.resize(9,9); //This happens in the constructor P.clear(); //This happens in the constructor //The following runs without errors //identity_matrix<double> identity(3); //This causes a run time error. identity_matrix<double> identity; identity.resize(3); topleft(P) = initial[0] * identity; return 0; }

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backporting filesystem v3
by Arash Abghari 14 Mar '11

14 Mar '11

Hi, I wonder if it is possible to backport filesystem v3 to 1.40 by replacing source folder from 1.46. Thanks Arash

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boost::mutex over a socket
by Marco Piacentini 14 Mar '11

14 Mar '11

Hi guys...I've 2 thread and I would like that one of these performs a synchronous read, menawhile the other performs a synchrounous write...adn obviously they share the same socket.....the signature of the functions are the following: length=boost::asio::read(socket_,boost::asio::buffer(msg,sizeof(msg)), ec); boost::asio::write(socket_,boost::asio::buffer(msgToSend,sizeof(msgToSend))); socket_ is a private field of the classe Server. How can I use the mutex to perform concurrently and safetly these operations? Thanks..

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[GIL] Compilation times
by Germán Diago 14 Mar '11

14 Mar '11

Hello. I'm using g++-4.4 with boost libraries and they're great. However, I have to use some image manipulation algorithms for two types of images (rgb8 and gray). I'm using it successfully, however, compilation times have increased a lot: I use apply_operation and any_image and any_image_view with two types each (rgb8 and gray8) Is there a way to decrease compile times? Thanks in advance.

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Small logic::tribool riddle
by Thomas Jarosch 14 Mar '11

14 Mar '11

Hello, here's a small boost::logic::tribool riddle: -<snip>------------------------------------- #include <iostream> #include <boost/logic/tribool.hpp> int main(void) { boost::logic::tribool foo(boost::logic::indeterminate); if (foo != true) { std::cout << "reached1\n"; } if (foo == boost::logic::indeterminate) { std::cout << "reached2\n"; } return 0; } -<snap>------------------------------------- Try to determine the printed result without looking at the boost::logic::tribool implementation / documentation. Intuitive? A coworker just shot himself in the foot... Best regards, Thomas Jarosch

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Re: [Boost-users] Boost-users Digest, Vol 2660, Issue 1
by Leon Sit 14 Mar '11

14 Mar '11

> > ---------- Forwarded message ---------- > From: Joel Falcou <joel.falcou(a)lri.fr> > To: boost-users(a)lists.boost.org > Date: Sat, 12 Mar 2011 08:24:53 +0100 > Subject: Re: [Boost-users] [proto] Object got sliced when passed by > reference > I just compiled your smaple using g++-4.5 and i got: > > logical_and( > logical_or( > terminal(4baseI2F1E) > , terminal(4baseI2F2E) > ) > , terminal(4baseI2F3E) > ) > hodqhoqw > 0 > > Why is I think the correct answer. So this is tied to some MSVC specific > behavior, i guess mayeb on how the terminal< base<_> const &> is matched. > matching terminal< base<_> > should be enough I think no ? Could you try ? > > HTH > > > > Thats what I did at the very beginning but fail. So I moved on to try const& but still fail. Before I started using proto, I hand-craft some overloaded operator to return the expression object too but failed with the same error. This makes me think that it is a compiler bug too. Should I try something else too?

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[hash] Performance & distribution, variable bit width
by Sebastian Karlsson 14 Mar '11

14 Mar '11

As I use boost::hash quite a bit I have a few questions which the documentation seems to leave out. First of all it would be terrific if there was a performance & distribution benchmark as a part of the documentation to make it easier to evaluate the merits of using it. Secondly I'm a bit stumped on why the return value is fixed to size_t for a couple of reasons. Bit width of size_t isn't guaranteed to be constant, wouldn't this severely affect the distribution properties of the hashing algorithm used? Furthermore it would be great if the user could choose the bit width of the hash. Often the birthday problem is relevant, and being able to swap to using a 64 bit hash easily is something that doesn't seem possible but often desirable. Kind regards, Sebastian Karlsson

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punits][accumulators] buggy behavior for min accumulator of quantities
by alfC 14 Mar '11

14 Mar '11

Hi, Sometimes it is difficult to make boost::units quantities with other libraries. For example to have boost::accumulators mean work with units, one has to specialize division by integer for quantities. In this example the accumulators and units compiles out of the box but gives an incorrect answer. #include<boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/min.hpp> // or other stat features #include <boost/accumulators/statistics/max.hpp> // or other stat features #include<boost/units/systems/si.hpp> #include<boost/units/io.hpp> using namespace boost::accumulators; using namespace boost::units; int main(){ accumulator_set<quantity<si::time>, features<tag::min, tag::max> > a; a(2.1*si::second); a(2.0*si::second); a(4.1*si::second); std::cout << extract::min(a)<< " " << extract::max(a)<< std::endl ; return 0; } It prints: 0 s 4.1 s instead of: 2.1 s 4.1 s So, it seems that the min extractor fails for quantities. I would like to know if there is a way to correctly specialize "min" for quantities. (By the way, std::min for quantities works fine). However the behavior is unfortunate in the first place. Regardless of the solution I would label this as a bug of one of the two libraries. Thank you, Alfredo

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Preventing iostreams from accessing freed memory
by Adam Nielsen 14 Mar '11

14 Mar '11

Hi all, I'm unable to prevent Boost iostreams from accessing memory once it has been freed, and I'm hoping someone here familiar with iostreams has some advice. As far as I can tell, when I push a standard iostream onto a filter, the filter holds on to a reference of it. If this happens inside a function, then when the function returns the iostream is freed, followed by the filter. In its destructor the filter tries to perform a flush/close and promptly segfaults, as it is trying to access the iostream which has just been freed. There is a set_auto_close() function I can call on the filter which sounds like it would do the trick, but it doesn't and according to the docs it's because it "does not prevent the Filters and Devices in the chain from being closed [flushed] automatically if the chain is complete at destruction." So is there any way I can prevent a filtering_stream from performing I/O in its destructor? Thanks, Adam.

1 1

[property tree][json]how to create empty array?
by Kulti 12 Mar '11

12 Mar '11

Hi, all! It's possible to get following output from boost::property_tree::json_parser::write_json ? { "id": "id", "method": "test_method", "params": [] } I know how to create array with some items, but when I try to create empty array, I've get "params": ""

3 3

temporary filenames
by Kraus Philipp 12 Mar '11

12 Mar '11

Hello, is there any implementation for creating temporary files names? I'm using tmpnam, but it can be dangerous. On posix systems I can use mkstemp. Is there any save implementation within the boost (perhaps in the iostreams)? Thanks Phil

2 2

boost-users@lists.boost.org
by Stephen Hewitt 12 Mar '11

12 Mar '11

I have recently upgraded to Boost 1.46 and am having trouble compiling the following simple program (Using Visual Studio 2005): // Error.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <tchar.h> #include <iostream> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/json_parser.hpp> void Go() { boost::property_tree::ptree t; boost::property_tree::read_json(std::cin, t); } int _tmain(int argc, _TCHAR* argv[]) { Go(); return 0; } Here are the errors I get: 1>------ Build started: Project: Error, Configuration: Debug Win32 ------ 1>Compiling... 1>stdafx.cpp 1>Compiling... 1>Error.cpp 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1> c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(178) : while compiling class template member function 'boost::property_tree::json_parser::json_grammar<Ptree>::definition<Scanner>::definition(const boost::property_tree::json_parser::json_grammar<Ptree> &)' 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> Scanner=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\impl\grammar.ipp(279) : see reference to class template instantiation 'boost::property_tree::json_parser::json_grammar<Ptree>::definition<Scanner>' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> Scanner=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\impl\grammar.ipp(298) : see reference to function template instantiation 'void boost::spirit::classic::impl::call_helper<0>::do_<result_t,definition_t,ScannerT>(RT &,DefinitionT &,const ScannerT &)' being compiled 1> with 1> [ 1> ScannerT=scanner_t, 1> RT=result_t, 1> DefinitionT=definition_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\grammar.hpp(55) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::impl::grammar_parser_parse<0,boost::property_tree::json_parser::json_grammar<Ptree>,boost::spirit::classic::parser_context<>,ScannerT>(const boost::spirit::classic::grammar<DerivedT> *,const ScannerT &)' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> ScannerT=scanner_t, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree> 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\non_terminal\grammar.hpp(65) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::grammar<DerivedT>::parse_main<ScannerT>(const ScannerT &) const' being compiled 1> with 1> [ 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ScannerT=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\scanner\impl\skipper.ipp(109) : see reference to function template instantiation 'boost::spirit::classic::match<boost::spirit::classic::nil_t> boost::spirit::classic::grammar<DerivedT>::parse<scanner_t>(const ScannerT &) const' being compiled 1> with 1> [ 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ScannerT=scanner_t 1> ] 1> c:\libraries\boost_1_46_0\boost\spirit\home\classic\core\scanner\impl\skipper.ipp(155) : see reference to function template instantiation 'boost::spirit::classic::parse_info<IteratorT> boost::spirit::classic::impl::phrase_parser<SkipT>::parse<IteratorT,DerivedT>(const IteratorT &,const IteratorT &,const ParserT &,const SkipT &)' being compiled 1> with 1> [ 1> IteratorT=It, 1> SkipT=boost::spirit::classic::alternative<boost::spirit::classic::alternative<boost::spirit::classic::space_parser,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::alternative<boost::spirit::classic::eol_parser,boost::spirit::classic::end_parser>,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> ParserT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree> 1> ] 1> c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(312) : see reference to function template instantiation 'boost::spirit::classic::parse_info<IteratorT> boost::spirit::classic::parse<std::_Vector_iterator<_Ty,_Alloc>,DerivedT,boost::spirit::classic::alternative<A,B>>(const IteratorT &,const IteratorT &,const boost::spirit::classic::parser<DerivedT> &,const boost::spirit::classic::parser<boost::spirit::classic::alternative<A,B>> &)' being compiled 1> with 1> [ 1> IteratorT=It, 1> _Ty=Ch, 1> _Alloc=std::allocator<char>, 1> DerivedT=boost::property_tree::json_parser::json_grammar<boost::property_tree::ptree>, 1> A=boost::spirit::classic::alternative<boost::spirit::classic::space_parser,boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::alternative<boost::spirit::classic::eol_parser,boost::spirit::classic::end_parser>,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme>>, 1> B=boost::spirit::classic::confix_parser<boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::kleene_star<boost::spirit::classic::anychar_parser>,boost::spirit::classic::impl::string_as_parser::type,boost::spirit::classic::unary_parser_category,boost::spirit::classic::non_nested,boost::spirit::classic::is_lexeme> 1> ] 1> c:\libraries\boost_1_46_0\boost\property_tree\json_parser.hpp(45) : see reference to function template instantiation 'void boost::property_tree::json_parser::read_json_internal<Ptree>(std::basic_istream<_Elem,_Traits> &,Ptree &,const std::string &)' being compiled 1> with 1> [ 1> Ptree=boost::property_tree::ptree, 1> _Elem=char, 1> _Traits=std::char_traits<char> 1> ] 1> c:\users\steve\documents\visual studio 2005\projects\error\error.cpp(13) : see reference to function template instantiation 'void boost::property_tree::json_parser::read_json<boost::property_tree::ptree>(std::basic_istream<_Elem,_Traits> &,Ptree &)' being compiled 1> with 1> [ 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> Ptree=boost::property_tree::ptree 1> ] 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(184) : error C3861: 'expect_object': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(185) : error C3861: 'expect_eoi': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(186) : error C3861: 'expect_objclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(187) : error C3861: 'expect_arrclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(188) : error C3861: 'expect_name': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(189) : error C3861: 'expect_colon': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(190) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2872: 'assertion' : ambiguous symbol 1> could be 'boost::assertion' 1> or 'c:\libraries\boost_1_46_0\boost\spirit\home\classic\error_handling\exceptions.hpp(187) : boost::spirit::classic::assertion' 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C2882: 'assertion' : illegal use of namespace identifier in expression 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(191) : error C3861: 'expect_escape': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(195) : error C3861: 'expect_object': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(196) : error C3861: 'expect_eoi': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(203) : error C3861: 'expect_objclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(209) : error C3861: 'expect_name': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(210) : error C3861: 'expect_colon': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(211) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(218) : error C3861: 'expect_arrclose': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(224) : error C3861: 'expect_value': identifier not found 1>c:\libraries\boost_1_46_0\boost\property_tree\detail\json_parser_read.hpp(250) : error C3861: 'expect_escape': identifier not found 1>Build log was saved at "file://c:\Users\Steve\Documents\Visual Studio 2005\Projects\Error\Debug\BuildLog.htm" 1>Error - 57 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

2 1

lambda : fabs( x - y )< eps
by er 12 Mar '11

12 Mar '11

I'm submitting this in case someone easily spots a less verbose representation of fabs( x - y )< eps than the one shown below and would like to share it. Using lambda (or variants) only (I know I can write my own functor class). Thanks. #include <cmath> #include <boost/function.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> #include <boost/numeric/conversion/bounds.hpp> typedef boost::function<double(double)> f1_; typedef boost::function<double(double, double)> f2_; typedef boost::function<bool(double)> g_; double eps = boost::numeric::bounds<double>::smallest(); f2_ f2 = lambda::bind( f1_( fabs ), lambda::_1 - lambda::_2 ) ; g_ g = ( eps > lambda::_1 ); BOOST_ASSERT( lambda::bind( g, lambda::bind( f2, lambda::_1, lambda::_2 ) )( 0.0, 0 * eps ) ); BOOST_ASSERT( !lambda::bind( g, lambda::bind( f2, lambda::_1, lambda::_2 ) )( 0.0, eps ) );

3 3